Several devices for holding gutter guards in place have been proposed in the past. All suffer shortcomings in that some require several steps in their manufacture; others require either a large amount of material or a material such as a spring steel for their construction, and others provide for attachment a screen on the roof side of a gutter and thereby impede the flow of water and can result in entrapment of debris, which further prevents flow of water into the gutter.
One prior art structure, made of a spring metal is described in U.S. Pat. No. 2,636,458. It is L shaped and has a series of tongues intended to hold a gutter screen in place. One of the tongues is placed over the edge of the screen and another engages the inner wall of the gutter.
In U.S. Pat. No. 2,717,561, there is described a gutter screen bracket with separate supports for the front and back inner edges of the gutter. Each support extends along the entire depth of the gutter and is adjustable as to height. A clip along one upper edge of the bracket holds one of the supports in place.
U.S. Pat. No. 2,810,173 discloses a clip having spaced clamping fingers for inserting a screen between them. Each finger has a flange for facilitating the insertion of the screen.
The clamps shown in U.S. Pat. No. 3,367,070 rely on spring tension to hold a screen on a drain. In each instance the clamp extends across the trough and onto the roof edge.
U.S. Pat. No. 3,420,378 discloses a hinged screen clamp, with provision for attaching the clamp to the interior lip of the outer edge of a gutter. In one modification the screen is inserted between a pair of brackets and in another design the upper bracket has a pair of tabs for securing the screen to the clamp.
The clamp of U.S. Pat. No. 4,036,761 has two rotational nodes. The screen fits into one of the nodes and the second is situated on the outer edge of the gutter flange. This provides the ability to rotate the screen up to about 170.degree. for cleaning.